A new category of equatorial F region plasma irregularities characterized by nearly sinusoidal waveforms in the ion number density N observed by the Atmosphere Explorer satellites has recently been discussed by Valladares et al. (1983) and Cragin et al. (1985). We present multisatellite scintillation observations made at Huancayo, Peru, and spaced- receiver drift measurements made at Ancon, Peru, associated with such irregularities observed by AE-E on a few nights in December 1979. Utilizing ray paths to various geostationary satellites, it is found that the irregularities grow and decay almost simultaneously in long-lived patches extending at least 1000 km in the E-W direction. The scintillations continue for a period of almost 6 hours, at a level that varies from moderate to fairly intense (S4=0.1--0.8 at 250 MHz), and these S4 fluctuations are quite well correlated, even over a distance of 1000 km. The irregularities constituting the large patch are found to drift eastward at a velocity of approximately 140 m/s. This and other such events are accompanied by the frequency spread signatures on Huancayo ionograms, as previously reported. The unique feature of the Fourier spectra associated with such bottomside sinusoidal (BSS) irregularities is the presence of Fresnel oscillations, which allow a determination of the velocity of the diffraction pattern perpendicular to the direction of the ray from the satellite to the ground station. The velocity so determined agrees well with the results of simultaneously performed spaced-receiver drift measurements. The presence of Fresnel oscillations indicates that the BSS irregularities occur in a relatively thin layer. However, while the scintillation data indicate a high-frequency roll-off with a spectral index of the order of -3to -4, the in situ tend to indicate that the index is of the order of -5 to -6. Modeling studies are necessary to resolve this difference.